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Sediment From Farms Threatens Scenic Lake Pepin

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ST. PAUL, Minn. (AP) — Early explorers described Lake Pepin as crystal clear with abundant fish and waterfowl. But the water flowing into Lake Pepin these days is a milky brown, and scientists say the upper third of the scenic lake could become filled in with sediment by the end of the century.

The river is depositing about 10 times as much sediment as it did before white settlers came to the area. According to a Minnesota Public Radio report Thursday, a Minnesota Pollution Control Agency draft study cites farm runoff as a major cause, and it says state officials have little leverage to compel changes that could save the lake.

Lake Pepin is a wide spot in the Mississippi River, about 20 miles long, stretching between Red Wing and Wabasha on the border between the Minnesota and Wisconsin bluffs. The sediment problem becomes graphically apparent about 40 miles upstream, where the muddy Minnesota River flows into the Mississippi at St. Paul, ending a 370-mile journey across some of the state’s most productive farmland.

“What you can see is two distinctly-colored bodies of water meeting: the relatively clean Mississippi and the relatively dirty Minnesota, which is loaded with sediments,” said Paul Labovitz, superintendent of the Mississippi National Rivera and Recreation area.

When that sediment gets deposited in Lake Pepin, it also affects animal life. Without clean gravel river beds, fish will lose their spawning habitat. Mussels that rely on a clean river bottom will disappear. Even insects are at risk.

“The whole food chain is affected when you cover the bottom of a river with silt and sediment,” Labovitz said. “Then it fills in, and it’s no longer a river. It might just become a stagnant wetland, and ultimately will become dry land.”

The problem is especially difficult to solve because about three-quarters of the sediment comes from many different sources in farm country, where federal water quality rules don’t apply.

“There’s no federal regulation that’s going to drive it,” said Norman Senjem, chief author of the MPCA study. “It’s up to the state of Minnesota.”

The study said most of the sediment doesn’t come directly from farm fields, but rather from stream banks. Over the years, farmers have redirected water flows to keep their fields dry. As a result, water now rushes out of ditches and into rivers too fast, eventually winding up in the Minnesota, then the Mississippi and finally Lake Pepin.

“We need to change the landscape in such a way that less water from the sky gets into the streams, to reduce the energy in those streams and the scouring out of sediment that that causes,” Senjem said.

While the MPCA is proposing goals to reduce sediments, it’s not advancing specific plans yet for how to make that happen. Senjem said the job is likely to fall to local governments. Counties generally rely on voluntary conservation efforts, such as programs that encourage farmers to rebuild wetlands, leave grass buffer strips near water bodies, and use modern tillage practices that reduce erosion.

So far, those programs have not persuaded enough farmers to make a difference. A separate MPCA study, released this week, found that aquatic life in the Minnesota River and its tributaries has not improved significantly in the last 20 years, despite extensive efforts.

Renville County in western Minnesota has 3,500 miles of drainage pipes installed under the soil that drain into nearly 800 miles of ditches. That’s more than the total miles of roads in the county. Nearly all of the ditches drain into the Minnesota River.

Larry Zupke, who maintains those ditches, said he would like to see a flexible set of rules to prevent erosion. His top wish is for the banks on many ditches to slope more gently, but said that would be a hard sell to some farmers because they’d lose that land for planting.

Tom Kalaher, a conservation technician with the Renville County Soil and Water Conservation District, said counties would have a better chance of limiting runoff if Congress changed the Farm Bill to encourage conservation practices. He said the federal farm program grossly favors production of corn and soybeans over protection of the environment.

“If you look at what’s spent on the conservation side, nationally, and what’s spent on the commodity side, the imbalance is horrific,” Kalaher said. “Until that changes, the results to the environment are going to be the same as what we’ve been seeing the 40 or 50 years.”